trigger PartsReturnTrigger on PartsReturn__c(before delete , after update , after undelete ) {
    ///删除的时候
    if(trigger.isBefore && trigger.isDelete)PartsLendingApplicationUtil.partsReturnBackToDetails(trigger.old,true );
     if(trigger.isAfter && (trigger.isUpdate || trigger.isUndelete ))PartsLendingApplicationUtil.partsReturnBackToDetails(trigger.new,false );

}